Techniques to Control Electronic Mail Delivery

1. An apparatus, comprising: a memory; a processor; and an internal message transfer agent coupled to the processor, the internal message transfer agent operative to: receive an electronic mail message from an external message transfer agent; retrieve a trust value associated with said external message transfer agent; determine a message delivery threshold for said external message transfer agent based on said trust value; determine that a current message flow rate value for said external message transfer agent does not exceed said message delivery threshold; accept the electronic mail message based on the current message flow rate value not exceeding the message delivery threshold; and increase said trust value in accordance with a growth rate in which a fully trusted level occurs at a saturation point, wherein the growth rate follows a logistic growth algorithm and the growth rate is based on one or both of a domain existence value and a sender existence value, the domain existence value representing an amount of time that a domain of the external message transfer agent has been in existence, the sender existence value representing an amount of time that a network address of the external message transfer agent has been in existence.

2. The apparatus of claim 1 , said internal message transfer agent operative to decrease said trust value based on a number of messages received within a given time period.

3. A system, comprising: a memory; a processor; a wireless communications interface coupled to the processor; and an internal message transfer agent coupled to the processor, said internal message transfer agent operative to: receive an electronic mail message from an external message transfer agent; retrieve a trust value associated with said external message transfer agent; determine a message delivery threshold for said external message transfer agent based on said trust value; determine that a current message flow rate value for said external message transfer agent does not exceed said message delivery threshold; accept the electronic mail message based on the current message flow rate value not exceeding the message delivery threshold; and increase said trust value in accordance with a growth rate in which a fully trusted level occurs at a saturation point, wherein the growth rate follows a logistic growth algorithm and the growth rate is based on one or both of a domain existence value and a sender existence value, the domain existence value representing an amount of time that a domain of the external message transfer agent has been in existence, the sender existence value representing an amount of time that a network address of the external message transfer agent has been in existence.

4. The system of claim 3 , said internal message transfer agent operative to decrease said trust value based on a number of messages received within a given time period.

5. A method, comprising: receiving an electronic mail message from an external message transfer agent; retrieving a trust value associated with said external message transfer agent; determining a message delivery threshold for said external message transfer agent based on said trust value; determining that a current message flow rate value for said external message transfer agent does not exceed said message delivery threshold; accepting the electronic mail message based on the current message flow rate value not exceeding the message delivery threshold; and increasing said trust value in accordance with a growth rate in which a fully trusted level occurs at a saturation point, wherein the growth rate follows a logistic growth algorithm and the growth rate is based on one or both of a domain existence value and a sender existence value, the domain existence value representing an amount of time that a domain of the external message transfer agent has been in existence, the sender existence value representing an amount of time that a network address of the external message transfer agent has been in existence.

6. An article comprising a machine-readable medium, wherein the machine-readable medium is not a signal, the machine-readable medium containing instructions that if executed enable a system to: receive an electronic mail message from an external message transfer agent; retrieve a trust value associated with said external message transfer agent; determine a message delivery threshold for said external message transfer agent based on said trust value; determine that a current message flow rate value for said external message transfer agent does not exceed said message delivery threshold; accept the electronic mail message based on the current message flow rate value not exceeding the message delivery threshold; and increase said trust value in accordance with a growth rate in which a fully trusted level occurs at a saturation point, wherein the growth rate follows a logistic growth algorithm and the growth rate is based on one or both of a domain existence value and a sender existence value, the domain existence value representing an amount of time that a domain of the external message transfer agent has been in existence, the sender existence value representing an amount of time that a network address of the external message transfer agent has been in existence.